The invention relates to offshore oil production and in particular to a method and apparatus for pulling in and anchoring a pipeline for a production riser system.
A production riser system will include a central riser with a plurality of peripherally located production risers. The production risers are used to produce oil to a surface location where it is treated and sent down through the central riser to a sales line for delivery of the oil. The central riser is connected to an anchor pile and must withstand all of the forces imposed on the production riser system. This riser will normally include a spool piece or mandrel with a flow connection being teed off of the central riser and provided with a pipe connection a short distance from the central riser.
This requires that the sales line be pulled in and remotely connected at this pipe joint. Apparatus for remotely making this connection has proved to be cumbersome and complicated, with the consequent diminished confidence in its reliability of operation.
Arrangement of pull-in apparatus to locate the pipeline at a precise location, while this apparatus takes the required pull-in loads has also proven to be difficult.
According to the invention, the remote connection adjacent the riser is eliminated; and the pipeline may be precisely located with low forces imposed on the pull-in structures.